In an incineration process it is desired to convert the residual or fixed carbon to carbon dioxide. The reaction of oxygen in air supplied to the combustion chamber with the carbon will result in the generation of carbon dioxide, but this reaction is exothermic, resulting in the release of heat from the reaction process. If this exothermic reaction is not controlled, the increased heat liberated through the reaction process can raise the temperature in the combustion chamber to a point where glass and metals may melt, resulting in the formation of clinkers. In order to reduce the high localized temperatures in the combustion chamber, it has been proposed in the past to introduce steam into the combustion chamber. The steam will react with the fixed carbon to form carbon monoxide and hydrogen, which is an endothermic reaction, absorbing heat from the combustion chamber and thereby reducing the high localized temperatures. The carbon monoxide and hydrogen formed in this reaction are subsequently burned in secondary zones of combustion to form carbon dioxide and water vapor.
By reducing the high localized temperatures in the combustion chamber by the introduction of steam, clinker formation is prevented, and the conversion of the fixed carbon to carbon dioxide is maximized.
In the past, steam has been injected into the combustion chamber through separate steam lines. In a typical incinerator having a steam injection system, the waste is moved longitudinally through the combustion chamber and air and steam are sequentially introduced at spaced locations along the length of the combustion chamber. This system does not produce a uniform reduction of temperature throughout the combustion chamber, but instead results in temperature fluctuations in which the temperature will rise as the waste passes over an air inlet tube and will subsequently be reduced as the waste approaches a steam entry tube. Furthermore, this conventional system requires the use of auxiliary steam lines, over and above the normal air supply lines, and during periods when steam is not being introduced the steam pipes can become overheated with possible damage.